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QGIS 3.4 calculate date, add month

Selecting by month in date/time field using ArcGIS Desktop?Add a certain number of days for a date fieldCalculate date field using date variable and time attribute in a feature classMapBasic subtract date columnsArcMap - Field Calculator / Calculate Value - extract month of median date between two datesQGIS: Symbolize by date field based on current dateLimited field type options QGIS 3.4Add Date to raster layers in raster stack in RCalculate date difference (days) with expressions (QGIS)

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2

I want to add a number of months to a date to get a new date. I have a date-field "date", an integer-field "months" and a date-field "new_date". I want to calculate the "new_date" by adding the "months" to the date. I did it with the expression:
"date"+ to_interval( concat ( to_string("months"), ' months'))
For example: "date"= 2019-06-04, "months" = 12,
the result ("newd_date") is: 2020-05-29, but I want to have: 2020-06-04.
It seems that QGIS is calculating each month with 30 days. Is there a way to add the exact months?

qgis expression date calculate-values

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edited 7 hours ago

Nane

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2

I want to add a number of months to a date to get a new date. I have a date-field "date", an integer-field "months" and a date-field "new_date". I want to calculate the "new_date" by adding the "months" to the date. I did it with the expression:
"date"+ to_interval( concat ( to_string("months"), ' months'))
For example: "date"= 2019-06-04, "months" = 12,
the result ("newd_date") is: 2020-05-29, but I want to have: 2020-06-04.
It seems that QGIS is calculating each month with 30 days. Is there a way to add the exact months?

qgis expression date calculate-values

share|improve this question

edited 7 hours ago

Nane

asked 8 hours ago

NaneNane

1122 bronze badges

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Nane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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add a comment
 | 

I want to add a number of months to a date to get a new date. I have a date-field "date", an integer-field "months" and a date-field "new_date". I want to calculate the "new_date" by adding the "months" to the date. I did it with the expression:
"date"+ to_interval( concat ( to_string("months"), ' months'))
For example: "date"= 2019-06-04, "months" = 12,
the result ("newd_date") is: 2020-05-29, but I want to have: 2020-06-04.
It seems that QGIS is calculating each month with 30 days. Is there a way to add the exact months?

qgis expression date calculate-values

share|improve this question

edited 7 hours ago

Nane

asked 8 hours ago

NaneNane

1122 bronze badges

New contributor

Nane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 7 hours ago

Nane

asked 8 hours ago

NaneNane

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Nane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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share|improve this question

edited 7 hours ago

Nane

asked 8 hours ago

NaneNane

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Nane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 8 hours ago

NaneNane

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New contributor

Nane is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked 8 hours ago

NaneNane

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What a shame the to_interval expression treats each month as 30 days!

Here's an ugly expression which will do what you want:

   to_date(concat(year("date")+floor("months"/12), '-',

     right('0' || ((month("date")+"months")%12) , 2),'-', 

     right('0' || day("date"),2)))

It breaks the date down into year, month and day, then uses the "months" field to add the relevant amount of years and months, then concatenates the values to make a string to convert to a date. The to_date expression is very particular about the input format - the month and day must be two digits - so the right expressions are used to pad out single digit months/days with a leading zero.

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answered 3 hours ago

M BainM Bain

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1

What a shame the to_interval expression treats each month as 30 days!

Here's an ugly expression which will do what you want:

   to_date(concat(year("date")+floor("months"/12), '-',

     right('0' || ((month("date")+"months")%12) , 2),'-', 

     right('0' || day("date"),2)))

It breaks the date down into year, month and day, then uses the "months" field to add the relevant amount of years and months, then concatenates the values to make a string to convert to a date. The to_date expression is very particular about the input format - the month and day must be two digits - so the right expressions are used to pad out single digit months/days with a leading zero.

share|improve this answer

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges

add a comment
 | 

1

What a shame the to_interval expression treats each month as 30 days!

Here's an ugly expression which will do what you want:

   to_date(concat(year("date")+floor("months"/12), '-',

     right('0' || ((month("date")+"months")%12) , 2),'-', 

     right('0' || day("date"),2)))

It breaks the date down into year, month and day, then uses the "months" field to add the relevant amount of years and months, then concatenates the values to make a string to convert to a date. The to_date expression is very particular about the input format - the month and day must be two digits - so the right expressions are used to pad out single digit months/days with a leading zero.

share|improve this answer

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges

add a comment
 | 

What a shame the to_interval expression treats each month as 30 days!

Here's an ugly expression which will do what you want:

   to_date(concat(year("date")+floor("months"/12), '-',

     right('0' || ((month("date")+"months")%12) , 2),'-', 

     right('0' || day("date"),2)))

It breaks the date down into year, month and day, then uses the "months" field to add the relevant amount of years and months, then concatenates the values to make a string to convert to a date. The to_date expression is very particular about the input format - the month and day must be two digits - so the right expressions are used to pad out single digit months/days with a leading zero.

share|improve this answer

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges

   to_date(concat(year("date")+floor("months"/12), '-',

     right('0' || ((month("date")+"months")%12) , 2),'-', 

     right('0' || day("date"),2)))

share|improve this answer

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges

answered 3 hours ago

M BainM Bain

54411 silver badge55 bronze badges